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                  <a href="#gst-plugins-bad-libs-GstAggregator.description" class="shortcut">Description</a></span>
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<a name="gst-plugins-bad-libs-GstAggregator"></a><div class="titlepage"></div>
<div class="refnamediv"><table width="100%"><tr>
<td valign="top">
<h2><span class="refentrytitle"><a name="gst-plugins-bad-libs-GstAggregator.top_of_page"></a>GstAggregator</span></h2>
<p>GstAggregator — manages a set of pads with the purpose of
aggregating their buffers.</p>
</td>
<td class="gallery_image" valign="top" align="right"></td>
</tr></table></div>
<div class="refsect1">
<a name="gst-plugins-bad-libs-GstAggregator.functions"></a><h2>Functions</h2>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="functions_return">
<col class="functions_name">
</colgroup>
<tbody>
<tr>
<td class="function_type">
<a href="/usr/share/gtk-doc/html/gstreamer-1.0GstPad.html#GstFlowReturn"><span class="returnvalue">GstFlowReturn</span></a>
</td>
<td class="function_name">
<a class="link" href="gst-plugins-bad-libs-GstAggregator.html#gst-aggregator-finish-buffer" title="gst_aggregator_finish_buffer ()">gst_aggregator_finish_buffer</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">void</span>
</td>
<td class="function_name">
<a class="link" href="gst-plugins-bad-libs-GstAggregator.html#gst-aggregator-set-src-caps" title="gst_aggregator_set_src_caps ()">gst_aggregator_set_src_caps</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<a href="/usr/share/gtk-doc/html/glibglib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>
</td>
<td class="function_name">
<a class="link" href="gst-plugins-bad-libs-GstAggregator.html#gst-aggregator-iterate-sinkpads" title="gst_aggregator_iterate_sinkpads ()">gst_aggregator_iterate_sinkpads</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<a href="/usr/share/gtk-doc/html/gstreamer-1.0GstClock.html#GstClockTime"><span class="returnvalue">GstClockTime</span></a>
</td>
<td class="function_name">
<a class="link" href="gst-plugins-bad-libs-GstAggregator.html#gst-aggregator-get-latency" title="gst_aggregator_get_latency ()">gst_aggregator_get_latency</a> <span class="c_punctuation">()</span>
</td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect1">
<a name="gst-plugins-bad-libs-GstAggregator.other"></a><h2>Types and Values</h2>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="name">
<col class="description">
</colgroup>
<tbody>
<tr>
<td class="datatype_keyword">struct</td>
<td class="function_name"><a class="link" href="gst-plugins-bad-libs-GstAggregator.html#GstAggregator" title="struct GstAggregator">GstAggregator</a></td>
</tr>
<tr>
<td class="datatype_keyword">struct</td>
<td class="function_name"><a class="link" href="gst-plugins-bad-libs-GstAggregator.html#GstAggregatorClass" title="struct GstAggregatorClass">GstAggregatorClass</a></td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect1">
<a name="gst-plugins-bad-libs-GstAggregator.description"></a><h2>Description</h2>
<p>Manages a set of pads with the purpose of aggregating their buffers.
Control is given to the subclass when all pads have data.</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem"><p>
   Base class for mixers and muxers. Subclasses should at least implement
   the <a class="link" href="gst-plugins-bad-libs-GstAggregator.html#GstAggregatorClass.aggregate"><code class="function">GstAggregatorClass.aggregate()</code></a> virtual method.
 </p></li>
<li class="listitem"><p>
   When data is queued on all pads, tha aggregate vmethod is called.
 </p></li>
<li class="listitem"><p>
   One can peek at the data on any given GstAggregatorPad with the
   <a class="link" href="gst-plugins-bad-libs-GstAggregatorPad.html#gst-aggregator-pad-get-buffer" title="gst_aggregator_pad_get_buffer ()"><code class="function">gst_aggregator_pad_get_buffer()</code></a> method, and take ownership of it
   with the <a class="link" href="gst-plugins-bad-libs-GstAggregatorPad.html#gst-aggregator-pad-steal-buffer" title="gst_aggregator_pad_steal_buffer ()"><code class="function">gst_aggregator_pad_steal_buffer()</code></a> method. When a buffer
   has been taken with <code class="function">steal_buffer()</code>, a new buffer can be queued
   on that pad.
 </p></li>
<li class="listitem"><p>
   If the subclass wishes to push a buffer downstream in its aggregate
   implementation, it should do so through the
   <a class="link" href="gst-plugins-bad-libs-GstAggregator.html#gst-aggregator-finish-buffer" title="gst_aggregator_finish_buffer ()"><code class="function">gst_aggregator_finish_buffer()</code></a> method. This method will take care
   of sending and ordering mandatory events such as stream start, caps
   and segment.
 </p></li>
<li class="listitem"><p>
   Same goes for EOS events, which should not be pushed directly by the
   subclass, it should instead return GST_FLOW_EOS in its aggregate
   implementation.
 </p></li>
<li class="listitem"><p>
   Note that the aggregator logic regarding gap event handling is to turn
   these into gap buffers with matching PTS and duration. It will also
   flag these buffers with GST_BUFFER_FLAG_GAP and GST_BUFFER_FLAG_DROPPABLE
   to ease their identification and subsequent processing.
 </p></li>
</ul></div>
</div>
<div class="refsect1">
<a name="gst-plugins-bad-libs-GstAggregator.functions_details"></a><h2>Functions</h2>
<div class="refsect2">
<a name="gst-aggregator-finish-buffer"></a><h3>gst_aggregator_finish_buffer ()</h3>
<pre class="programlisting"><a href="/usr/share/gtk-doc/html/gstreamer-1.0GstPad.html#GstFlowReturn"><span class="returnvalue">GstFlowReturn</span></a>
gst_aggregator_finish_buffer (<em class="parameter"><code><a class="link" href="gst-plugins-bad-libs-GstAggregator.html#GstAggregator" title="struct GstAggregator"><span class="type">GstAggregator</span></a> *agg</code></em>,
                              <em class="parameter"><code><a href="/usr/share/gtk-doc/html/gstreamer-1.0GstBuffer.html#GstBuffer-struct"><span class="type">GstBuffer</span></a> *buffer</code></em>);</pre>
<p>This method will push the provided output buffer downstream. If needed,
mandatory events such as stream-start, caps, and segment events will be
sent before pushing the buffer.</p>
<div class="refsect3">
<a name="gst-aggregator-finish-buffer.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>self</p></td>
<td class="parameter_description"><p>The <a class="link" href="gst-plugins-bad-libs-GstAggregator.html#GstAggregator" title="struct GstAggregator"><span class="type">GstAggregator</span></a></p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>buffer</p></td>
<td class="parameter_description"><p> the <a href="/usr/share/gtk-doc/html/gstreamer-1.0GstBuffer.html#GstBuffer-struct"><span class="type">GstBuffer</span></a> to push. </p></td>
<td class="parameter_annotations"><span class="annotation">[<acronym title="Free data after the code is done."><span class="acronym">transfer full</span></acronym>]</span></td>
</tr>
</tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="gst-aggregator-set-src-caps"></a><h3>gst_aggregator_set_src_caps ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
gst_aggregator_set_src_caps (<em class="parameter"><code><a class="link" href="gst-plugins-bad-libs-GstAggregator.html#GstAggregator" title="struct GstAggregator"><span class="type">GstAggregator</span></a> *agg</code></em>,
                             <em class="parameter"><code><a href="/usr/share/gtk-doc/html/gstreamer-1.0GstCaps.html#GstCaps-struct"><span class="type">GstCaps</span></a> *caps</code></em>);</pre>
<p>Sets the caps to be used on the src pad.</p>
<div class="refsect3">
<a name="gst-aggregator-set-src-caps.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>self</p></td>
<td class="parameter_description"><p>The <a class="link" href="gst-plugins-bad-libs-GstAggregator.html#GstAggregator" title="struct GstAggregator"><span class="type">GstAggregator</span></a></p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>caps</p></td>
<td class="parameter_description"><p>The <a href="/usr/share/gtk-doc/html/gstreamer-1.0GstCaps.html#GstCaps-struct"><span class="type">GstCaps</span></a> to set on the src pad.</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="gst-aggregator-iterate-sinkpads"></a><h3>gst_aggregator_iterate_sinkpads ()</h3>
<pre class="programlisting"><a href="/usr/share/gtk-doc/html/glibglib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>
gst_aggregator_iterate_sinkpads (<em class="parameter"><code><a class="link" href="gst-plugins-bad-libs-GstAggregator.html#GstAggregator" title="struct GstAggregator"><span class="type">GstAggregator</span></a> *self</code></em>,
                                 <em class="parameter"><code><span class="type">GstAggregatorPadForeachFunc</span> func</code></em>,
                                 <em class="parameter"><code><a href="/usr/share/gtk-doc/html/glibglib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> user_data</code></em>);</pre>
<p>Iterate the sinkpads of aggregator to call a function on them.</p>
<p>This method guarantees that <em class="parameter"><code>func</code></em>
 will be called only once for each
sink pad.</p>
<div class="refsect3">
<a name="gst-aggregator-iterate-sinkpads.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>self</p></td>
<td class="parameter_description"><p>The <a class="link" href="gst-plugins-bad-libs-GstAggregator.html#GstAggregator" title="struct GstAggregator"><span class="type">GstAggregator</span></a></p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>func</p></td>
<td class="parameter_description"><p> The function to call. </p></td>
<td class="parameter_annotations"><span class="annotation">[<acronym title="The callback is valid only during the call to the method."><span class="acronym">scope call</span></acronym>]</span></td>
</tr>
<tr>
<td class="parameter_name"><p>user_data</p></td>
<td class="parameter_description"><p> The data to pass to <em class="parameter"><code>func</code></em>
. </p></td>
<td class="parameter_annotations"><span class="annotation">[<acronym title="This parameter is a 'user_data', for callbacks; many bindings can pass NULL here."><span class="acronym">closure</span></acronym>]</span></td>
</tr>
</tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="gst-aggregator-get-latency"></a><h3>gst_aggregator_get_latency ()</h3>
<pre class="programlisting"><a href="/usr/share/gtk-doc/html/gstreamer-1.0GstClock.html#GstClockTime"><span class="returnvalue">GstClockTime</span></a>
gst_aggregator_get_latency (<em class="parameter"><code><a class="link" href="gst-plugins-bad-libs-GstAggregator.html#GstAggregator" title="struct GstAggregator"><span class="type">GstAggregator</span></a> *self</code></em>);</pre>
<p>Retrieves the latency values reported by <em class="parameter"><code>self</code></em>
 in response to the latency
query, or <a href="/usr/share/gtk-doc/html/gstreamer-1.0GstClock.html#GST-CLOCK-TIME-NONE:CAPS"><code class="literal">GST_CLOCK_TIME_NONE</code></a> if there is not live source connected and the element
will not wait for the clock.</p>
<p>Typically only called by subclasses.</p>
<div class="refsect3">
<a name="gst-aggregator-get-latency.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>self</p></td>
<td class="parameter_description"><p>a <a class="link" href="gst-plugins-bad-libs-GstAggregator.html#GstAggregator" title="struct GstAggregator"><span class="type">GstAggregator</span></a></p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="gst-aggregator-get-latency.returns"></a><h4>Returns</h4>
<p> The latency or <a href="/usr/share/gtk-doc/html/gstreamer-1.0GstClock.html#GST-CLOCK-TIME-NONE:CAPS"><code class="literal">GST_CLOCK_TIME_NONE</code></a> if the element does not sync</p>
</div>
</div>
</div>
<div class="refsect1">
<a name="gst-plugins-bad-libs-GstAggregator.other_details"></a><h2>Types and Values</h2>
<div class="refsect2">
<a name="GstAggregator"></a><h3>struct GstAggregator</h3>
<pre class="programlisting">struct GstAggregator {
  GstElement               parent;

  GstPad                *  srcpad;

  /* Only access with the object lock held */
  GstSegment               segment;
};
</pre>
<p>Aggregator base class object structure.</p>
<div class="refsect3">
<a name="GstAggregator.members"></a><h4>Members</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="300px" class="struct_members_name">
<col class="struct_members_description">
<col width="200px" class="struct_members_annotations">
</colgroup>
<tbody>
<tr>
<td class="struct_member_name"><p><a href="/usr/share/gtk-doc/html/gstreamer-1.0GstElement.html#GstElement-struct"><span class="type">GstElement</span></a> <em class="structfield"><code><a name="GstAggregator.parent"></a>parent</code></em>;</p></td>
<td> </td>
<td> </td>
</tr>
<tr>
<td class="struct_member_name"><p><a href="/usr/share/gtk-doc/html/gstreamer-1.0GstPad.html#GstPad-struct"><span class="type">GstPad</span></a> *<em class="structfield"><code><a name="GstAggregator.srcpad"></a>srcpad</code></em>;</p></td>
<td class="struct_member_description"><p>the aggregator's source pad</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><a href="/usr/share/gtk-doc/html/gstreamer-1.0GstSegment.html#GstSegment-struct"><span class="type">GstSegment</span></a> <em class="structfield"><code><a name="GstAggregator.segment"></a>segment</code></em>;</p></td>
<td class="struct_member_description"><p>the output segment</p></td>
<td class="struct_member_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="GstAggregatorClass"></a><h3>struct GstAggregatorClass</h3>
<pre class="programlisting">struct GstAggregatorClass {
  GstElementClass   parent_class;

  GType             sinkpads_type;

  GstFlowReturn     (*flush)          (GstAggregator    *  aggregator);

  GstFlowReturn     (*clip)           (GstAggregator    *  aggregator,
                                       GstAggregatorPad *  aggregator_pad,
                                       GstBuffer        *  buf,
                                       GstBuffer        ** outbuf);

  /* sinkpads virtual methods */
  gboolean          (*sink_event)     (GstAggregator    *  aggregator,
                                       GstAggregatorPad *  aggregator_pad,
                                       GstEvent         *  event);

  gboolean          (*sink_query)     (GstAggregator    *  aggregator,
                                       GstAggregatorPad *  aggregator_pad,
                                       GstQuery         *  query);

  /* srcpad virtual methods */
  gboolean          (*src_event)      (GstAggregator    *  aggregator,
                                       GstEvent         *  event);

  gboolean          (*src_query)      (GstAggregator    *  aggregator,
                                       GstQuery         *  query);

  gboolean          (*src_activate)   (GstAggregator    *  aggregator,
                                       GstPadMode          mode,
                                       gboolean            active);

  GstFlowReturn     (*aggregate)      (GstAggregator    *  aggregator,
                                       gboolean            timeout);

  gboolean          (*stop)           (GstAggregator    *  aggregator);

  gboolean          (*start)          (GstAggregator    *  aggregator);

  GstClockTime      (*get_next_time)  (GstAggregator    *  aggregator);

  GstAggregatorPad * (*create_new_pad) (GstAggregator  * self,
                                        GstPadTemplate * templ,
                                        const gchar    * req_name,
                                        const GstCaps  * caps);
};
</pre>
<p>The aggregator base class will handle in a thread-safe way all manners of
concurrent flushes, seeks, pad additions and removals, leaving to the
subclass the responsibility of clipping buffers, and aggregating buffers in
the way the implementor sees fit.</p>
<p>It will also take care of event ordering (stream-start, segment, eos).</p>
<p>Basically, a basic implementation will override <em class="parameter"><code>aggregate</code></em>
, and call
_finish_buffer from inside that function.</p>
<div class="refsect3">
<a name="GstAggregatorClass.members"></a><h4>Members</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="300px" class="struct_members_name">
<col class="struct_members_description">
<col width="200px" class="struct_members_annotations">
</colgroup>
<tbody>
<tr>
<td class="struct_member_name"><p><a href="/usr/share/gtk-doc/html/gobjectgobject-Type-Information.html#GType"><span class="type">GType</span></a> <em class="structfield"><code><a name="GstAggregatorClass.sinkpads-type"></a>sinkpads_type</code></em>;</p></td>
<td class="struct_member_description"><p>Optional.
The type of the pads that should be created when
GstElement.request_new_pad is called.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.flush"></a>flush</code></em> ()</p></td>
<td class="struct_member_description"><p>Optional.
Called after a succesful flushing seek, once all the flush
stops have been received. Flush pad-specific data in
<a class="link" href="gst-plugins-bad-libs-GstAggregatorPad.html#GstAggregatorPad" title="struct GstAggregatorPad"><span class="type">GstAggregatorPad</span></a>-&gt;flush.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.clip"></a>clip</code></em> ()</p></td>
<td class="struct_member_description"><p>Optional.
Called when a buffer is received on a sink pad, the task
of clipping it and translating it to the current segment
falls on the subclass.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.sink-event"></a>sink_event</code></em> ()</p></td>
<td class="struct_member_description"><p>Optional.
Called when an event is received on a sink pad, the subclass
should always chain up.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.sink-query"></a>sink_query</code></em> ()</p></td>
<td class="struct_member_description"><p>Optional.
Called when a query is received on a sink pad, the subclass
should always chain up.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.src-event"></a>src_event</code></em> ()</p></td>
<td class="struct_member_description"><p>Optional.
Called when an event is received on the src pad, the subclass
should always chain up.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.src-query"></a>src_query</code></em> ()</p></td>
<td class="struct_member_description"><p>Optional.
Called when a query is received on the src pad, the subclass
should always chain up.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.src-activate"></a>src_activate</code></em> ()</p></td>
<td class="struct_member_description"><p>Optional.
Called when the src pad is activated, it will start/stop its
pad task right after that call.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.aggregate"></a>aggregate</code></em> ()</p></td>
<td class="struct_member_description"><p>Mandatory.
Called when buffers are queued on all sinkpads. Classes
should iterate the GstElement-&gt;sinkpads and peek or steal
buffers from the <a href="gst-plugins-bad-libs-GstAggregatorPad.html#GstAggregatorPad"><span class="type">GstAggregatorPads</span></a>. If the subclass returns
GST_FLOW_EOS, sending of the eos event will be taken care
of. Once / if a buffer has been constructed from the
aggregated buffers, the subclass should call _finish_buffer.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.stop"></a>stop</code></em> ()</p></td>
<td class="struct_member_description"><p>Optional.
Called when the element goes from PAUSED to READY.
The subclass should free all resources and reset its state.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.start"></a>start</code></em> ()</p></td>
<td class="struct_member_description"><p>Optional.
Called when the element goes from READY to PAUSED.
The subclass should get ready to process
aggregated buffers.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.get-next-time"></a>get_next_time</code></em> ()</p></td>
<td class="struct_member_description"><p>Optional.
Called when the element needs to know the running time of the next
rendered buffer for live pipelines. This causes deadline
based aggregation to occur. Defaults to returning
GST_CLOCK_TIME_NONE causing the element to wait for buffers
on all sink pads before aggregating.</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><em class="structfield"><code><a name="GstAggregatorClass.create-new-pad"></a>create_new_pad</code></em> ()</p></td>
<td> </td>
<td> </td>
</tr>
</tbody>
</table></div>
</div>
</div>
</div>
<div class="refsect1">
<a name="gst-plugins-bad-libs-GstAggregator.see-also"></a><h2>See Also</h2>
<p>gstcollectpads for historical reasons.</p>
</div>
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